Rehoboth, MA – Oldcastle Precast’s Skilton Road Bridge Rehabilitation was recipient of Precast/Prestressed Concrete Institute’s (PCI) 2016 Design Excellence Award.
Skilton Road Bridge, a one lane, dry stone masonry arch bridge originally built in 1865, required special consideration to preserve the historic nature of the bridge, increase the width to accommodate two traffic lanes, and add a sidewalk on one side of the bridge.
The designers considered several potential solutions to rehabilitate the structure, and ultimately decided to install a new superstructure consisting of precast, prestressed concrete slabs that would bear the load of the new road structure, thus preserving and protecting the entire historic structure below. “The use of prestressed, precast concrete beams enabled the bridge to be widened while minimizing the impact on the existing bridge,” says William Andres, associate with Tata and Howard, the engineer for the project.
A key advantage to utilizing precast, prestressed concrete on this project was that the precast concrete slabs were cast while demolition and construction of new beam seats were being completed, which shortened the project timeline and minimized disruption. It also reduced the time needed to detour traffic around the construction site, and eliminated the need for scaffolding and formwork. “That made it made it less expensive than a cast-in-place design,” Andres says.
The precast concrete slabs were prestressed to resist the required construction loads and to carry the required in place design loads. Instead of orienting them in the normal longitudinal direction, the slabs were installed transverse to the roadway, extending out roughly five feet beyond the existing stone masonry walls. Installation of the slabs took just one day.